1. Field of the Invention
The present invention relates to a rope-like wire-saw having a large number of abrasive grains firmly fixed to the outer circumferential surface thereof by metal, and further relates to a method for manufacturing such a wire-saw.
2. Description of the Related Arts
As a conventional wire-saw, there is widely known a impregnated metal-bonded wire-saw in which abrasive grains and metal powder are mixed and molded, then the molded mixture is burned together with beads to produce beads having an abrasive layer portion, and the beads are fixed to a metal wire rope. Such a wire-saw is used for cutting a stone or a concrete structure. (For example, see JP-B-49-2231, and JP-B-51-38473)
There is also widely known a wire-saw in which abrasive grains are brought into direct contact with beads, without using any metal bonding, to fix the abrasive grains to the beads by precipitating nickel or the like in gaps among the abrasive grains by electroplating, chemical plating, or the like, and the beads are fixed to a wire.
In a conventional metal-bonded grinding tool, a cutting edge is exposed by self-dressing caused by chips of a subject to be cut. Therefore, the cutting performance varies conspicuously in accordance with the choice of a bonding composition. In addition, the amount and shape of such chips vary in accordance with machining conditions. Therefore, the cutting performance varies also in accordance with the matching (compatibility) between the bonding composition and the subject to be cut.
In addition, the bonding composition is worn to expose abrasive grains. However, because there is no chemical linkage between the bonding composition and the abrasive grains, the abrasive grains easily fall away from the bonding composition. Therefore, the rate with which the abrasive grains can be engaged in cutting in the whole of the tool is so low as to cause unstable cutting and reduction in the life of the tool.
Further, as shown in FIG. 1, in a conventional impregnated metal-bonded wire-saw 1, abrasive layer beads 6 are fixed to a core wire 3 at a predetermined interval by caulking, and further fixed by a covering material 8 of plastic, rubber, or the like. Accordingly, flexibility or stress dispersion performance essential for the wire is blocked.
It is therefore an object of the present invention to solve fundamentally the foregoing problems.
It is another object of the present invention to provide a wire-saw which does not depend on self-dressing caused by a subject to be cut; in which the cutting performance is immutable in safety and for a long time; and which is long in life and excellent in cutting performance; and to provide a method for manufacturing such a wire-saw.
The wire-saw according to the present invention comprises: a saw-wire body rolled up like a cylindrical coil; a large number of abrasive grains firmly fixed to an outer surface of the cylindrical coil of the saw-wire body by metal; and a rope-like core wire fixedly inserted into an inner space of the cylindrical coil of the saw-wire body over a whole length of said cylindrical coil.
Further, the method for manufacturing a wire-saw, according to the present invention, comprises the steps of: kneading additive materials with powder containing copper alloy or the like as a main component to thereby form a mixture; continuously disposing the mixture on an outer surface of a saw-wire body rolled up like a cylindrical coil; coating a surface of the continuously disposed mixture with an active metal brazing material; scattering and disposing a large number of abrasive grains on the brazing material; heating the saw-wire body as a whole to a temperature to melt the alloy component partially or wholly in a vacuum or reducing or neutral atmosphere so that the abrasive grains are fixed firmly to positions where the abrasive grains are disposed respectively by the metal component; and fixedly inserting a rope-like core wire into an inner space of the cylindrical coil of the saw-wire body over a whole length of said cylindrical coil.
In the wire-saw according to the present invention, the core wire is composed of a steel wire in the same manner as that in a wire rope of a conventional wire-saw.
On the other hand, the abrasive grains may be selected from a group composed of diamond, cubic boron nitride, silicon carbide, and cemented carbide.
In addition, the coil-like saw-wire body may be fixed to the core wire by the friction generated by elastic deformation of the coil-like saw-wire body. Further, at least the surface of the core wire may be covered by rubber, plastic or the like, in order to prevent the core wire from corrosion.
Further, it is extremely preferable that opposite end portions of the core wire forming the wire-saw are connected with each other endlessly through a wire connection sleeve having an outer circumferential surface to which a large number of abrasive grains are firmly fixed. Thus, the cutting performance of the wire-saw can be enhanced.
With such a configuration, a continuous cutting edge having the abrasive grains on the saw-wire body in the wire-saw can be formed according to the present invention. In addition, the saw-wire body is rolled like a cylindrical coil. Accordingly, the sharpness and life of the cutting edge can be controlled by changing the pitch of the coil to adjust the average distance among the abrasive grains. Further, the saw-wire body is made of steel similarly to the core wire, and has a continuous coil-like shape so that the cutting edge of the abrasive grains is always in contact with the subject to be cut. Accordingly, vibrations apt to be generated by intermittent cutting can be reduced. Further, as a feature of the coil-like shape, the spiral angle can be always kept with respect to the cutting direction. Accordingly, self rotation is caused on the whole of the wire-saw in the work time. Thus, one-sided abrasion of the wire can be prevented, extremely advantageously on the elongation of the life of the tools.
In addition, the coil-like saw-wire body gives tension and flexibility to the core wire and makes it possible to cut a small-curvature portion of a subject to be cut by the saw-wire body while suitable stress dispersion can be provided against the tension produced by driving the wire-saw.